热心人来帮忙看一下为何这么奇怪？

Question

和书上一样的处理MouseLeave事件的代码总是没反应！...type
  TMyBtn2 = class(TCustomControl)
  private
    FOnMouseLeave: TNotifyEvent;
    procedure WMMouseLeave(var Msg: TMessage); message WM_MOUSELEAVE;        
  published
    property OnMouseLeave: TNotifyEvent read FOnMouseLeave write FOnMouseLeave;    
  end;...procedure TMyBtn2.WMMouseLeave(var Msg: TMessage);
begin
  inherited;
  if Assigned(FOnMouseLeave) then FOnMouseLeave(Self);
end;...

Answer 1

//CM_MOUSELEAVE
type
  TMyBtn2 = class(TCustomControl)
  private
    FOnMouseLeave: TNotifyEvent;
    procedure CMMouseLeave(var Msg: TMessage); message CM_MOUSELEAVE;        
  published
    property OnMouseLeave: TNotifyEvent read FOnMouseLeave write FOnMouseLeave;    
  end;...procedure TMyBtn2.CMMouseLeave(var Msg: TMessage);
begin
  inherited;
  if Assigned(FOnMouseLeave) then FOnMouseLeave(Self);
end;...